Bromine filled bipost lamp with a high-temperature resistant glass envelope

ABSTRACT

A relatively low-cost, high-maintenance incandescible bipost lamp is described. The lamp has a vitreous, high-temperatureresistant glass envelope, an operative atmosphere containing bromine, with the bipost base secured to a flared mount structure which comprises a portion of the envelope of the lamp. The filament is tungsten, and the metallic support elements within the envelope are also made of tungsten.

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:91?! UNITED STATES PATENTS 1,809,661 6/1931 MBLQE EQ EE.

[54] BOMINE FILLED BIPOS'I LAMP WITH A HIGH-TEMPERATURE RESISTANT GLASS ENVELOPE [72] Inventor: Arislide R. DeCaro, Edison, NJ.

313/315 3,314,331 4/1967 Wiley....................... ....313/315X Cortion, Pitt- [73] Assignee: Westinghouse Electric s irsw Primary Examiner-Raymond F. Hossfeld V Attorney-A. T. Stratton, W. D. Palmer and W. G. Sutcliff [22] Filed: Sept. 24, 1970 BROMINE FILLED lBlllPOST LAMP WITH A HIGH- TEMPERATURE RESISTANT GLASS ENVELOPE BACKGROUND OF THE INVENTION A bipost based incandescible lamp is traditionally a highwattage lamp utilized in applications requiring high-lighting levels and good color rendition. The base for the traditional bipost lamp has been a glass saucer sealed to a preformed bulbous portion of the envelope. The conductive lead-ins are usually made via two internally exposed copper thimbles which are sealed to the saucer, with the filament mount frame fastened to the thimbles for mechanical and electrical support and contact respectively. The lamp fill is traditionally inert gas. The use of copper thimbles and such a seal precludes the use of a halogen atmosphere for establishing a tungstenhalogen cycle within the lamp. In the now familiar brominefilled lamp, a quartz envelope has been employed with a molybdenum ribbon seal arrangement for providing electrical conductors through the envelope. This typical quartz press sealing arrangement for halogen lamps would make the bipost based lamp relatively expensive.

SUMMARY OF THE INVENTION A relatively inexpensive, high-maintenance light output, bipost based, incandescible lamp has been provided. The lamp combination comprises a light-transmissive envelope of vitreous, high-temperature-resistant glass, which encloses an operative atmosphere of inert gas and bromine. An incandescible tungsten filament is substantially centrally disposed within the envelope. A portion of the envelope is comprised of a flared mount structure which extends inwardly toward the filament, with the mount structure having a thickened press portion at the inwardly extending end through which refractory metal lead-in conductors are sealed. The lead-in conductors are electrically connected to the ends of the incandescible filament to thereby provide mechanical support for the coil. The flared portion of the mount structure has the bipost base secured thereto, with the lead-in conductors electrically connected to the base post.

BRIEF DESCRIPTION OF THE DRAWINGS The sole figure is an elevational view partly in section of an embodiment ofthe present invention.

DESCRIPTION OF THE PREFERRED EMBODIMENT The invention can be best understood by reference to an exemplary embodiment such as shown in the sole figure. The incandescible lamp combination comprises a light-transmissive envelope 12 formed of a vitreous, high-temperature resistant glass, for example an aluminosilicate glass made by the Coming Glass Company having an approximate composition of about 55% silica, about 22% alumina, about 13% magnesia, about 5% CaO, and about 5% B 0 An operative atmosphere of inert gas is provided, of for example, nitrogen at about l,000 millimeters pressure, and bromine which is readily provided by dosing the lamp with about 0.2 percent by volume methylene bromide. An incandescible tungsten coil 14 is substantially centrally disposed within the envelope 12. The tungsten coil 14 is by way of example a planar coil array with quartz support rods 15 disposed at opposite ends of the coil array in the same plane as the coil array. A plurality of tung' sten support rods 17 having one end embedded in the quartz rods 15 and the other end attached to the coil 14 maintain the planar coil array in position. The glass base portion 16 of the envelope 12 comprises a flared mount structure 18 comprising a flared extremity portion 24 which is joined to the envelope to form the glass base, with an elongated portion 19 of the mount structure 18 extending inwardly towards the coil. The flared mount structure 18 includes an evacuating and dosing aperture 32 through which the lamp is evacuated and dosed during manufacture, with the aperture being sealed after the lamp is closed with the operative atmosphere. The mount structure 18 has a thickened pressed portion 20 at the inwardly extending end thereof, and through which refractory metal lead-in conductors 22 are sealed. Lead-in conductors 22 are electrically connected to the ends of the coil 14, and thereby provide mechanical support for the coil. The bipost base 26 comprises a generally cylindrical top portion 34 which is dimensioned to receive the glass base end 16 of the envelope. A conventional basing cement 30 mechanically connects the glass envelope to the base 26 which is formed of a conventional basing metal. A generally circular mounting plate 36 is affixed to the end of the cylindrical top portion which extends away from the envelope. The mounting plate 36 has two apertures 38 therethrough, with hollowed electrical insulators 40 mechanically affixed therein. The base pins 28 are mechanically connected to the insulators 40, and are electrically connected to the portion of the lead-ins 22 which extend external of the envelope.

In a particular embodiment a 1,000 watt incandescible tungsten coil is centrally disposed within a T-l2 generally cylindrical lamp envelope. The designation T-l 2 is a standard term of the art which indicates that the diameter of the cylindrical lamp envelope is 1% inches. The overall length of the envelope from the bottom of the flare of the mount structure portion of the envelope to the top of the envelope is about 4 inches. The mount structure itself is about 1 inches long. The lamp volume ofthis embodiment is approximately 78 cc.

The lamp combination described is readily usable in a standard bipost socket and will maintain a relatively substantially constant light output during life. These advantages have been achieved while decreasing the cost for the lamp combination. The lamp can be substituted for a standard single-ended quartz-halogen lamp combination in application.

The aluminosilicate glass described by way of example has high-temperature limitations for an annealed envelope at nor mal service of 200 C., with an extreme limit of 650 C., and for a tempered envelope the normal device is limited to about 400 C., with an extreme limit of about 450 C.

It is readily apparent that the present invention, is not limited to the embodiment described, but can be practiced with variations in the lamp filament and envelope size. Other high-temperature resistant glasses can be employed provided they can be formed into the flared mount structure member required.

I claim as my invention:

1. An incandescible bipost based lamp combination comprising, a light-transmissive envelope of vitreous, high-temperature-resistant glass mechanically affixed to a bipost base, an operative atmosphere of inert gas and bromine, an incandescible tungsten coil substantially centrally disposed within said envelope, a portion of said envelope comprising a flared mount structure which extends inwardly toward said coil, said mount structure having a thickened press portion at the inwardly extending end through which refractory metal lead-in conductors are sealed, said lead-in conductors are electrically connected to the ends of said coil and thereby provide mechanical support for said coil, the flared portion of said mount structure having said bipost base secured thereto, with the lead-in conductors electrically connected to the base posts.

2. The combination as specified in claim 1, wherein said vitreous, high-temperature resistant glass is alumino silicate glass.

3. The combination as specified in claim 1, wherein the refractory metal lead-in conductors are extended to form the refractory metal coil mount structure, and said refractory metal is tungsten.

4. The combination as specified in claim 1, wherein said coil comprises a planar coil array with quartz support rods disposed at opposite ends of said array in the same plane as said coil array, with a plurality of tungsten support rods having one end embedded in said quartz rods and the other end attached to said coil to maintain said planar array in position.

5. The combination as specified in claim 1, wherein said envelope is generally cylindrical.

6. The combination as specified in claim 1, wherein said flared mount structure includes an evacuating and dosing aperture which is sealed after dosing of said lamp.

7. The combination as specified in claim 1, wherein said bipost base comprises a generally cylindrical top portion which is dimensional to receive the glass base end of said lamp, a circular mounting plate affixed to the end of said cylindrical top portion which extends away from said envelope, said mounting plate having two apertures therethrough, two bipost pins mechanically attached to said plate but electrically insulated from the rest of said bipost base, and electrically connected to the lamp lead-in conductors via a conductor which extends through said apertures in said plate, with the cylindrical portion of said bipost base being mechanically joined to said glass base portion of the lamp via basing elementv 8. An incandescible bipost based lamp combination comprising. a light-transmissive envelope of vitreous, high-temperature-resistant glass mechanically affixed to a bipost base, an operative atmosphere of inert gas and bromine, an incandescible tungsten coil substantially centrally disposed within said envelope, a portion of said envelope comprising a flared mount structure, the flared extremity portion of which is joined to said envelope to form a glass base for said lamp, the rest of said mount structure extending inwardly toward said coil disposed within said envelope, said mount structure terminating at the inwardly extending end in a thickened press portion through which refractory metal lead-in conductors are sealed, the internally extending portion ofsaid lead-in conductors are electrically connected to the ends of said coil and thereby provide mechanical support for said coil, the flared portion of said mount structure having said bipost base secured thereto, with the portion of said lead-in conductors external of said lamp envelope electrically connected to the base posts. 

2. The combination as specified in claim 1, wherein said vitreous, high-temperature resistant glass is alumino silicate glass.
 3. The combination as specified in claim 1, wherein the refractory metal lead-in conductors are extended to form the refractory metal coil mount structure, and said refractory metal is tungsten.
 4. The combination as specified in claim 1, wherein said coil comprises a planar coil array with quartz support rods disposed at opposite ends of said array in the same plane as said coil array, with a plurality of tungsten support rods having one end embedded in said quartz rods and the other end attached to said coil to maintain said planar array in position.
 5. The combination as specified in claim 1, wherein said envelope is generally cylindrical.
 6. The combination as specified in claim 1, wherein said flared mount structure includes an evacuating and dosing aperture which is sealed after dosing of said lamp.
 7. The combination as specified in claim 1, wherein said bipost base comprises a generally cylindrical top portion which is dimensional to receive the glass base end of said lamp, a circular mounting plate affixed to the end of said cylindrical top portion which extends away from said envelope, said mounting plate having two apertures therethrough, two bipost pins mechanically attached to said plate but electrically insulated from the rest of said bipost base, and electrically connected to the lamp lead-in conductors via a conductor which extends through said apertures in said plate, with the cylindrical portion of said bipost base being mechanically joined to said glass base portion of the lamp via basing element.
 8. An incandescible bipost based lamp combination comprising, a light-transmissive envelope of vitreous, high-temperature-resistant glass mechanically affixed to a bipost base, an operative atmosphere of inert gas and bromine, an incandescible tungsten coil substantially centrally disposed within said envelope, a portion of said envelope comprising a flared mount structure, the flared extremity portion of which is joined to said envelope to form a glass base for said lamp, the rest of said mount structure extending inwardly toward said coil disposed within said envelope, said mount structure terminating at the inwardly extending end in a thickened press portion through which refractory metal lead-in conductors are sealed, the internally extending portion of said lead-in conductors are electrically connected to the ends of said coil and thereby provide mechanical support for said coil, the flared portion of said mount structure having said bipost base secured thereto, with the portion of said lead-in conductors external of said lamp envelope electrically connected to the base posts. 